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Posted

i rode my friends 421 and it is way to much for our trails we even did some timed runs and mines a little faster so with that being said lets hear about the 392 servals

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Posted

Take the 421 and subtract about 5-7 hp and about 3ft lbs and there's your 392...The smaller motor would have a slightly peakier (if that's a word) power band

which may make the situation worse.

 

Like mentioned earlier, it's all about set up and rider ability..The tighter and more technical the terrain, the more this plays a factor.

Posted

well my cylinders are junk now and i dont want to buy someones junk cylinders off ebay thats when i found the servals but i cant find any info on a 392 my plan is to make a 392 long rod im not sure about carbs or pipes yet im thinking cpi pipes with 28 or 30mm carbs but any info you have i can use let me know

Posted

28mm would be good or even your stock one's...For trail riding I would run Pro Circuit pipes. They make the most low end power of any pipe on the market

If I were in your shoes I would be on the phone with FAST or M&M atv..Those 2 guys have built enough servals, to answer any questions you have.

Check the sponsor forum for contact info.

Posted

you will have to get your crank welded and at this point but new bearings on I would think, that being said I would consider the 421 serval again since you have to split the cases. with the bigger serval you are able to ride them in a higher gear in the trail and with mine it kinda acts like a 4 stroke where you dont need to shift very much ( I have the 10mil serval) I think the 392 serval would be great for someone who just bought a new welded crank and now wants to do the topend

Posted (edited)

my crank went out thats why my cylinders are junk now i have to rebuild top and bottom i read that a long rod crank last a little longer so thats what im going with

Edited by trailshee23
Posted

I ride a 421 serval and it absolutely pulls away from all the 4 strokes and bolt on banshees that I ride with (anything from black diamond trails to hair scrambles).

 

For you, I would suggest you save some cash. Pick up a 4 mil crank and some stock bore/port cylinders. Send them out for a woods or MX style port. A stroked "low-mid" port motor will be your best bet in tight trails. Since you keep stressing tight trails and woods, your first concern should be the suspension/tires/brakes. This will ultimately make you faster than any motor will in these conditions.

Posted

your friend needs to learn to ride....as there shouldn't be any reason that a stock stroke ported bike is being a 421 serval setup. something is wrong....

 

we don't know the complete set up of both bike's, you can't take a 4 mil. set up for trailing and go drag race a stock stroke bike set up for drags. Don't under estimate stock stroke bike's set up for drags, they rev out faster

Posted

i have elka shocks yfz brakes and itp hd tires so im good with all that and yes my brothers shee revs like a sob im not sur what he did to it i posted the last known mods but i do know it was the same as mine but a smaller bore who knows now he wont tell he hasnt had the bottom end apart tho just the top

Posted

There is another thread on here that shows dyno numbers with Pro Circuits, CPI's, and one other pipe. The Pro Circuits seemed to do great on a 421 Serval. I ran pro circuits on my ported 4 mill stock cyl and that thing ripped with a very usable power band. You might want to consider trying the Pro Circuits first. 28mm

Carbs would work real well on a 392 and help preserve some low end.

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